Recently, as energy consumption is increased, the development on a solar cell to convert solar energy into electrical energy has been performed.
In particular, a CIGS-based solar cell has been extensively used, in which the CIGS-based solar cell is a PN hetero junction device having a substrate structure including a glass substrate, a metallic back electrode layer, a P type CIGS-based light absorbing layer, a high resistance buffer layer, and an N type electrode layer.
In addition, studies have been performed to improve electrical characteristics such as low resistance and high transmittance in a solar cell.